Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given that this is a simple read-only tool with comprehensive annotations (readOnlyHint, destructiveHint, idempotentHint, openWorldHint) and no parameters, the description is minimally adequate. However, without an output schema, the description should ideally specify what format the server time is returned in (e.g., timestamp, ISO string). The current description leaves this ambiguous.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.